WO2023096469A1 - Electrode tab welding apparatus, electrode tab welding method, and secondary battery - Google Patents

Abstract

The present invention relates to an electrode tab welding apparatus for welding together electrode tabs protruding from an electrode assembly, the apparatus comprising: a guide part which is provided to gather the electrode tabs in a predetermined gathering region; a welding part which is provided to weld the electrode tabs gathered by the guide part; and a bending part which is provided to bend the electrode assembly before the electrode tabs are welded by the welding part, the electrode assembly being bent so that at least some of the electrode tabs increase in length from the electrode assembly to the gathering region.

Description

Electrode tab welding device, electrode tab welding method and secondary battery

Mutual Citation with Related Applications

This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0167738 dated November 29, 2021 and Korean Patent Application No. 10-2022-0163018 dated November 29, 2022, and All disclosed subject matter is incorporated as part of this specification.

technology field

The present invention relates to an electrode tab welding device, an electrode tab welding method, and a secondary battery.

In general, a secondary battery means a battery that can be charged and discharged, unlike a primary battery that cannot be charged, and is widely used in electronic devices such as mobile phones, laptop computers, and camcorders, or electric vehicles. In particular, since the lithium secondary battery has a larger capacity than a nickel-cadmium battery or a nickel-hydrogen battery and has a high energy density, the degree of its utilization is rapidly increasing.

Depending on the shape of the battery case, secondary batteries are classified into cylindrical batteries and prismatic batteries in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-type case made of an aluminum laminate sheet. It can be.

1 is a diagram showing an example of a pouch type secondary battery. The pouch-type secondary battery 1 includes an electrode assembly 10 formed by alternately stacking electrodes and a separator, and a pouch 20 (exterior material) in which the electrode assembly 10 is accommodated. Electrode tabs 15 may be connected to the electrodes of the electrode assembly 10 . The electrode tabs 15 may be welded to each other in a predetermined area and then connected to the electrode lead 17 . The pouch 20 includes an indented cup portion 21 for accommodating the electrode assembly 10 . The cup portion 21 of the pouch 20 may be formed of one or two. 1 illustrates a pouch 20 including a left cup portion and a right cup portion. Around the periphery of the cup portion 21, a peripheral portion 23 (terrace) is formed by sealing.

However, when a pulling force is applied to the electrode tab 15 due to the deformation of the peripheral portion 23 of the pouch 20, the electrode tab 15 may be gradually tightened and then disconnected. Alternatively, even when a pulling force is applied to the electrode tab 15 due to the expansion of the pouch 20 , the electrode tab 15 may be gradually tightened and then disconnected. Such disconnection is pointed out as a major cause of fire. In the case of a pouch-type secondary battery, the length of the peripheral part 23 is reduced to increase energy density according to the recent demand for high capacity and high performance, which is By reducing the 'length to the welding point', the risk of disconnection is further increased.

An object of the present invention is to increase the 'length from the electrode assembly to the welding point of the electrode tabs' of the electrode tab to prevent disconnection of the electrode tab even in a pouch-type secondary battery with high capacity and high performance, an electrode tab welding device, and an electrode It is to provide a tab welding method and a secondary battery.

In one example, an electrode tab welding device relates to a device for welding electrode tabs protruding from an electrode assembly to each other, a guide unit provided to gather the electrode tabs in a predetermined assembly area, and welding the electrode tabs gathered by the guide unit. A welding portion provided to do so, and a bending portion provided to bend the electrode assembly so that a length from the electrode assembly to the assembly area is increased in at least some of the electrode tabs before welding by the welding portion. there is.

In another example, when the guide unit considers that the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, a plane parallel to the ground is higher than the reference plane passing through the center of the electrode assembly in the vertical direction. It may be provided to gather the electrode tabs in the lower assembly area, and the bending part may be provided to bend an edge of the electrode assembly to which the electrode tabs are connected upward.

In another example, when the bending part considers that the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, a support block supporting one of the lower surface and the upper surface of the electrode assembly, and the lower surface of the electrode assembly and a pressing block for pressing the other one of the upper surface toward the one.

In another example, a point at which the support block supports any one of the lower and upper surfaces of the electrode assembly is outside the electrode assembly than a point at which the pressing block presses the other one of the lower and upper surfaces of the electrode assembly. can be located close to

In another example, the support block is provided to support an edge of the electrode assembly to which the electrode tabs are connected from a lower side, and the pressing block presses the edge supported by the support block from an upper side to a lower side for bending. can be arranged.

In another example, the support block may include an inclined surface positioned below the edge and gradually increasing in height toward the outside of the electrode assembly.

In another example, the electrode tab welding apparatus further includes a seating portion on which the electrode assembly is seated, and the bending portion is inside the seating portion when considering that the electrode and the separator of the electrode assembly are stacked in a vertical direction perpendicular to the ground. It may include a pressing block that is disposed and protrudes from an upper surface of the seating portion on which the lower surface of the electrode assembly is seated and presses an edge of the electrode assembly to which the electrode tabs are connected from the lower side.

In another example, the bending unit may further include a support block partially supporting an upper surface of the electrode assembly while being pressed by the press block.

In another example, the bending part includes a support block provided to support the edge of the electrode assembly to which the electrode tabs are connected from the lower side when the electrode and the separator of the electrode assembly are stacked in a vertical direction perpendicular to the ground can do.

In another example, an electrode tab welding device relates to an electrode tab welding device for welding electrode tabs protruding from an electrode assembly to each other, and includes a guide unit provided to gather the electrode tabs in a predetermined assembly area, and the guide unit A welding portion provided to weld the gathered electrode tabs, and prior to welding by the welding portion, in at least some of the electrode tabs, the electrodes of the electrode assembly and the separator are stacked so that the length from the electrode assembly to the assembly area is increased. A moving unit for relatively moving the electrode assembly with respect to the guide unit in a direction corresponding to the direction may be included.

In another example, an electrode tab welding method relates to a method of welding electrode tabs protruding from an electrode assembly to each other, (a) bending an edge of the electrode assembly to which the electrode tabs are connected, and (b) the electrode tabs. A step of welding the electrode tabs in a bent state of the assembly may be included.

In another example, the electrode tab welding method may further include collecting the electrode tabs before step (a) or between steps (a) and (b).

In another example, the electrode tab welding method may further include, after the step (b), restoring the electrode assembly by removing the force applied to the electrode assembly for bending the electrode assembly in the step (a). there is.

In another example, in step (a), when considering that the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, the lower surface and the lower surface of the edge in a state in which one of the lower and upper surfaces of the edge is supported It may be a step of pressing the other one of the upper surfaces toward the one.

In another example, a point supporting one of the lower and upper surfaces of the edge may be located closer to the outer side of the electrode assembly than a point pressing the other of the lower and upper surfaces of the edge.

In another example, a secondary battery is electrically connected to an electrode assembly, electrode tabs protruding from the electrode assembly, an exterior material accommodating the electrode assembly and the electrode tabs, and the electrode tabs, and a portion of the exterior material is An exposed electrode lead may be included, the electrode tabs may be coupled to each other in a predetermined bonding area, and a length of at least some of the electrode tabs from the electrode assembly to the bonding area is greater than a predetermined reference length. The reference length may be a minimum length from the electrode assembly to the coupling region in an individual electrode tab.

In another example, the increased length of at least some of the electrode tabs from the electrode assembly to the bonding area may increase as the electrode tab is located farther from the bonding area along the stacking direction of the electrode and the separator of the electrode assembly. and, the increased length may be a value obtained by subtracting the reference length from a length from the electrode assembly to the coupling region.

In another example, when the stacking direction is regarded as corresponding to the vertical direction, the bonding area may be positioned to correspond to the lowermost electrode tab among the electrode tabs of the electrode assembly, and the increased length of the electrode tabs is vertical. An upper electrode tab may be longer.

In another example, when the electrodes and separators of the electrode assembly are stacked in a vertical direction, electrode tabs passing through the bonding area and positioned above a reference plane orthogonal to the vertical direction and positioned below the reference plane The electrode tabs may have an asymmetrical length with respect to the reference plane.

According to the present invention, since the length from the electrode assembly to the assembly area (or welding area) can be increased in at least some of the electrode tabs by bending the electrode assembly, in the case of the battery manufactured according to the present invention, the periphery of the pouch Even if a pulling force is applied to the electrode tab due to deformation of the (terrace) or a pulling force is applied to the electrode tab due to expansion of the battery, the electrode tab may not be disconnected.

1 is a diagram showing an example of a pouch type secondary battery.

2A to 2D are diagrams for explaining one exemplary process that may be applied to welding electrode tabs of a pouch type secondary battery.

3 is a cross-sectional view showing a portion of a battery module in which several pouch-type batteries are accommodated in a case.

4 is a view showing an electrode tab welding apparatus according to a first embodiment of the present invention.

FIG. 5 is a view showing an unbent electrode assembly as opposed to the electrode assembly shown in FIG. 4 .

6A to 6E are views for explaining a method of welding electrode tabs using the welding apparatus of FIG. 4 .

7 is a view showing an electrode tab welding apparatus according to a second embodiment of the present invention.

8 is a view showing an electrode tab welding apparatus according to a third embodiment of the present invention.

9 is a view for explaining a modified example of a secondary battery according to a fourth embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily practice with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited or limited by the following examples.

In order to clearly describe the present invention, parts irrelevant to the description or detailed descriptions of related known technologies that may unnecessarily obscure the subject matter of the present invention have been omitted, and in this specification, reference numerals are added to the components of each drawing. In the specification, the same or similar reference numerals are used for the same or similar components throughout the specification.

In addition, the terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor appropriately defines the concept of terms in order to best describe his/her invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be done.

First, a process of welding electrode tabs of a pouch type secondary battery will be described with reference to FIG. 2 . 2 is a diagram for explaining an exemplary process that can be applied to welding electrode tabs of a pouch type secondary battery.

First, the electrode assembly 10 is prepared as shown in FIG. 2 (a). The electrode assembly 10 may be provided by stacking electrodes 11 and separators 13 . The electrode 11 includes an anode and a cathode. An electrode tab 15 may be connected to the electrode 11 . For reference, only the negative electrode tab 15 connected to the negative electrode is shown in FIG. 2 for convenience of description. The positive electrode tab connected to the positive electrode may also be provided in the electrode assembly 10 to extend in a direction different from the extension direction of the negative electrode tab 15 and may be welded in the same manner as the negative electrode tab. Next, the electrode tabs 15 are gathered as shown in FIG. 2(b). For example, the electrode tabs 15 may be gathered by pressing the electrode tabs 15 with the two rods 111 and 112 . Next, the electrode tabs 15 are welded through the welding part 120 as shown in FIG. 2(c).

Through these processes, as shown in FIG. 2(d), an electrode assembly 10 having electrode tabs 15 welded to each other in a predetermined welding area W can be manufactured. After connecting the electrode leads 17 (see FIG. 1) to the electrode tabs 15, the pouch type battery 1 may be manufactured by accommodating the electrode assembly 10 in a pouch 20 (see FIG. 1).

As shown in FIG. 3 , several pouch-type batteries 1 may be accommodated in one case C and manufactured as a battery module. 3 is a cross-sectional view showing a portion of a battery module in which several pouch-type batteries are accommodated in a case.

However, the peripheral portion 23 of the pouch 20 may be bent during manufacturing of the battery module. Deformation of the peripheral portion 23 may cause the electrode lead 17 to bend, thereby causing a pulling force on the electrode tab 15 connected to the electrode lead 17 (eg, refer to the electrode tab 15a in FIG. 3). ). Such force may pull the electrode tab 15 taut and cause disconnection of the electrode tab 15 . This force may appear larger in the outer electrode tab 15a. Even when the battery expands, the above problem of disconnection may be caused.

The present invention, which will be described in detail below, is to solve the above problem of disconnection.

Example 1

4 is a view showing an electrode tab welding apparatus according to a first embodiment of the present invention. The electrode tab welding device according to the first embodiment of the present invention relates to a device for welding electrode tabs 15 protruding from an electrode assembly 10 to each other, and as shown in FIG. 4, the guide part 110, the welding part ( 120) and a bending part 130. For reference, it will be seen that the electrode 11 and the separator 13 of the electrode assembly 10 are stacked in a vertical direction perpendicular to the ground. However, this is exemplary and the stacking direction of the electrode 11 and the separator 13 may vary depending on the direction in which the electrode assembly 10 is viewed. The contents of this embodiment can be applied to other embodiments as long as they do not conflict with each other.

The guide part 110 may be provided to gather the electrode tabs 15 in a predetermined gathering area G. For example, the guide part 110 may include a first rod 111 disposed above the electrode tabs 15 and a second rod 112 disposed below the electrode tabs 15. there is. The first rod 111 and the second rod 112 may move toward each other and press the electrode tabs 15 to gather the electrode tabs 15 in the gathering area G. In this process, the electrode tabs 15 may be bent toward the collection region G. Here, the gathering area G may be an area where the electrode tabs 15 , which are spaced apart from each other, are brought together by the guide part 110 . For reference, the guide unit may be implemented as a first press (not shown) that is stationary and a second press (not shown) that moves toward the first press.

The welding part 120 may be provided to weld the electrode tabs 15 collected by the guide part 110 . For example, the welding unit 120 may include a horn and an anvil for performing ultrasonic welding. Electrode leads 17 (see FIG. 1) for supplying electricity to the outside of the battery may be welded to the electrode tabs 15 welded by the welding part 120 . For reference, although the guide part 110 and the welding part 120 are shown separately in FIG. 4 , the guide part and the welding part may be connected to each other. For example, the first rod may be connected to the horn of the welding part and the second rod may be connected to the anvil of the welding part.

The bending part 130 may be provided to bend the electrode assembly 10 . The bending unit 130 may increase the reference length L of all or part of the electrode tabs 15 through bending. Here, the reference length L may be the 'length from the electrode assembly 10 to the assembly area G' of the electrode tab 15 .

For example, when the electrode assembly 10 of FIG. 5 is bent upward, as shown in FIG. 4, the right edge 19 of the electrode assembly 10 rises, and the left end of the electrode tab 15 (ie, , ends connected to the electrode assembly) are pulled upward, so that the 'length L from the electrode assembly 10 to the assembly area G' of the electrode tab 15 may increase. At this time, the remaining portion of the electrode tab 15 (eg, the portion of the electrode tab positioned to the right of the point pressed by the first and second rods in FIG. 5) may also be pulled to the left. FIG. 5 is a view showing an unbent electrode assembly as opposed to the electrode assembly shown in FIG. 4 . For reference, the guide unit 110 may press the electrode tabs 15 to a degree that allows the electrode tabs 15 to be pulled. To this end, the guide unit may include a roller (not shown) on a side contacting the electrode tab. For example, a roller may be provided at the lower end of the first rod and/or at the upper end of the second rod to rotate in contact with the electrode tab.

When the electrode tabs 15 are welded in such a bent state or after bending, the 'length L from the electrode assembly 10 to the assembly area G' of at least some of the electrode tabs 15 increases. Accordingly, the 'length from the electrode assembly 10 to the welding area W' of at least some of the electrode tabs 15 may also be increased. Such an increase in length can prevent or slow down disconnection caused by the electrode tab 15 being pulled tight. This is because, due to the length increase, the electrode tab 15 will be taut only if the electrode tab 15 is pulled more than before the length increase. For reference, the force applied to the electrode leads 17 (refer to FIG. 1 ) may be transferred to the electrode tabs 15 through a connection point between the electrode tabs 15 and the electrode lead 17 .

In the electrode tab welding apparatus of the present embodiment, the length from the electrode assembly 10 to the assembly area G is increased in at least some of the electrode tabs 15 before welding by the welding part 120, the electrode assembly 10 ) Since it includes the bending portion 130 provided to bend the electrode tab 15 due to deformation of the peripheral portion 23 (terrace) of the pouch 20 in the case of a battery manufactured by the electrode tab welding apparatus of the present embodiment, ), or even if a pulling force is applied to the electrode tab 15 due to battery expansion, the electrode tab 15 may not be disconnected.

The degree of bending of the electrode assembly 10 may be determined in consideration of the length increase required for the bending part 130 of the present embodiment to prevent disconnection. For example, in the case of a battery module in which the peripheral portion 23 of the pouch 20 is greatly deformed, the bending portion 130 may further bend the electrode assembly 10 . Such adjustment can be achieved by adjusting the size of the support block 131 to be described later.

Meanwhile, the set region G is a plane parallel to the ground and may be located below the reference plane P passing through the center of the electrode assembly 10 in the vertical direction. The guide unit 110 may gather the electrode tabs 15 in the gathering area G. At this time, the bending part 130 may bend the edge 19 of the electrode assembly 10 to which the electrode tabs 15 are connected upward. In FIG. 4 , an assembly area G positioned to correspond to the lowermost side of the electrode assembly 10 is illustrated.

When the edge 19 of the electrode assembly 10 is bent upward, the electrode tab (e.g., drawing The electrode tab of reference numeral 15b) may have an increased reference length (L) than before bending of the electrode assembly 10 . As the collection region G is positioned lower than the reference plane P, the number of electrode tabs 15 whose reference length L is increased by the bending portion 130 may increase. For reference, here, upper and lower may be relative concepts. For example, when the set region is located above the reference plane P, the bending part 130 may bend the edge 19 of the electrode assembly 10 downward.

Meanwhile, the bending part 130 of the present embodiment may include a support block 131 supporting one of a lower surface and an upper surface of the electrode assembly 10 . The bending part 130 of this embodiment may include a pressing block 133 that presses the other of the lower surface and the upper surface of the electrode assembly 10 toward one of the above-mentioned ones. The pressing block 133 may be provided to move in a vertical direction for pressing. 4 illustrates a support block 131 supporting the lower surface of the electrode assembly 10 and a pressing block 133 pressurizing the upper surface of the electrode assembly 10 toward the lower surface.

Since the electrode assembly 10 can be bent only by the support by the support block 131 , the bending portion 130 may include only the support block 131 . However, since the electrode assembly 10 can be more easily bent when the electrode assembly 10 is pressed with the pressing block 133 in a supported state by the support block 131, the bending portion 130 presses the support block 131 Block 133 may all be included.

A point where the support block 131 supports the electrode assembly 10 may be closer to the outer side of the electrode assembly 10 than a point where the pressure block 133 presses the electrode assembly 10 . For example, in FIG. 4 , a point where the support block 131 supports the lower surface of the electrode assembly 10 is located to the right of a point where the pressure block 133 presses the upper surface of the electrode assembly 10 . Through this positional relationship, the bending part 130 of the present embodiment can effectively bend the edge 19 of the electrode assembly 10 upward or downward.

As shown in FIG. 4 , the support block 131 may be provided to support the edge 19 of the electrode assembly 10 to which the electrode tabs 15 are connected from a lower side. The pressing block 133 may be provided to press the edge 19 of the electrode assembly 10 supported by the support block 131 from top to bottom for bending.

The support block 131 may be implemented in various shapes capable of supporting the electrode assembly 10 . For example, as shown in FIG. 4 , the support block 131 may be implemented in a shape including an inclined surface 131a supporting the lower side of the edge 19 of the electrode assembly 10 . The inclined surface 131a of the support block 131 is a surface located below the edge 19 and may be a surface that gradually increases in height toward the outside of the electrode assembly 10 (eg, to the right side of FIG. 4 ). When the support block 131 includes the inclined surface 131a, it is possible to support the edge 19 of the electrode assembly 10 while preventing the edge 19 of the electrode assembly 10 from being damaged. The press block 133 may also be implemented in various shapes capable of pressurizing the electrode assembly 10 . 4 illustrates a rod-shaped pressing block 133 .

Hereinafter, a welding process of the electrode tabs 15 through the welding device of the present embodiment will be described with reference to FIG. 6 . FIG. 6 is a view for explaining a method of welding electrode tabs using the welding apparatus of FIG. 4 .

First, the electrode assembly 10 is prepared as shown in FIG. 6 (a). At this time, the electrode assembly 10 may be seated on the seating portion 140 . The seating portion 140 may be a jig or die on which the electrode assembly 10 can be seated.

Next, the electrode tabs 15 are gathered as shown in FIG. 6(b). This may be implemented by the operation of the guide unit 110. For example, in a state in which the second rod 112 supports the electrode tabs 15 from the lower side, the first rod 111 presses the electrode tabs 15 from the upper side to the lower side so that the electrode tabs 15 ) can be gathered in the collection area (G).

Next, the electrode assembly 10 is bent as shown in FIG. 6(c). This may be implemented by the operation of the bending unit 130 . The bending part 130 may bend the edge 19 of the electrode assembly 10 to which the electrode tab 15 is connected. For example, the edge 19 of the electrode assembly 10 is bent by the pressing block 133 pressing the right upper surface of the edge 19 while the support block 131 supports the right lower surface of the edge 19. can do. For reference, when the electrode assembly 10 is seated on the seating portion 140, the support block 131 may already be disposed on the upper surface of the seating portion 140. Alternatively, the support block may be provided to protrude from the inside of the seating unit to the upper surface of the seating unit.

Next, as shown in FIG. 6(d), the electrode tabs 15 are welded through the welding part 120 in the bent state of the electrode assembly 10.

Through this process, in the case of at least some of the electrode tabs 15, the 'length L from the electrode assembly 10 to the assembly area G' can be increased, and in this state, the electrode tabs 15 can be welded together. As a result, in the case of at least some of the electrode tabs 15 (eg, the electrode tab of reference numeral 15c), as shown in FIG. 6(e), in contrast to the case where there is no bending process, the welding area (W) ) can be increased. For reference, although a process of bending the electrode assembly 10 after assembling the electrode tabs 15 is illustrated in FIG. 6 , it is also possible to gather the electrode tabs 15 after bending the electrode assembly 10 .

Meanwhile, after welding, the force applied to the electrode assembly 10 for bending of the electrode assembly 10 may be removed. For example, the pressure block 133 may be removed and the support block 131 may be moved upward. The electrode assembly 10 may return to its original shape by removing the force. Since the electrodes 11 and the separator 13 constituting the electrode assembly 10 have a certain degree of elasticity, they can be bent by application of force by the bending part 130, and restored to their original shapes by removing this force. It can be.

Example 2

7 is a view showing an electrode tab welding apparatus according to a second embodiment of the present invention. The welding device of Example 2 is different from the welding device of Example 1 in the support block and the pressure block. Hereinafter, the support block and the pressure block will be mainly described. For reference, the contents of this embodiment may be applied to other embodiments as long as they do not conflict with each other.

The bending part 230 of the present embodiment may include a pressing block 233 protruding from the seating part 240 on which the electrode assembly 10 is seated. The press block 233 is disposed inside the seating portion 240 and protrudes from the top surface of the seating portion 240 on which the lower surface of the electrode assembly 10 is seated to press the electrode assembly 10 . In this case, the pressing block 233 may press the edge 19 of the electrode assembly 10 to which the electrode tabs 15 are connected from the lower side. When the bending part 230 is configured in this way, the pressing block 233 can be protruded after the electrode assembly 10 is seated on the seating part 240, so that the electrode assembly 10 can be smoothly moved while needed (e.g., : After the electrode assembly is seated on the seating portion) Pressing by the pressing block 233 may be performed.

The bending unit 230 of this embodiment may include a driving unit 235 for vertically moving the pressing block 233 . For example, the drive unit 235 may be a cylinder from which a cylinder rod is drawn or drawn.

The bending portion 230 of this embodiment may include a support block 231 to support the electrode assembly 10 during pressurization by the press block 233 . The support block 231 may be provided to partially support the upper surface of the electrode assembly 10 . The support block 231 may support an area other than the area pressed by the pressure block 233 so as not to interfere with the bending of the electrode assembly 10 . For example, when the pressing block 233 presses the edge 19 of the electrode assembly 10, the support block 231 supports the electrode assembly 10 in an area other than the edge 19 of the electrode assembly 10. It may be provided to support the upper surface. The support block 231 may be provided to move in a vertical direction so as not to interfere with the seating of the electrode assembly 10 .

Example 3

8 is a view showing an electrode tab welding apparatus according to a third embodiment of the present invention. The welding apparatus of Example 3 is different from the welding apparatus of the above-described embodiments in a method of increasing the 'length from the electrode assembly to the assembly area' of the electrode tab. For reference, the contents of this embodiment may be applied to other embodiments as long as they do not conflict with each other.

The electrode tab welding device of the present embodiment relates to a device for welding electrode tabs protruding from an electrode assembly to each other, and may include a guide part 110 , a welding part 120 and a moving part 340 . The guide part 110 and the welding part 120 may be the same as the guide part 110 and the welding part 120 described above.

The moving unit 340 moves the electrode assembly 10 toward the guide unit 110 in a direction corresponding to the stacking direction of the electrode 11 and the separator 13 of the electrode assembly 10 (a vertical direction in FIG. 8 ). It may be arranged to move relative to each other. Because of the relative movement, the moving unit 340 may, for example, move the electrode assembly 10 upward in FIG. 8 away from the guide unit 110, or move the guide unit 110 downward in FIG. It can also be moved away from (10). 8 illustrates a moving unit 340 provided to move the electrode assembly 10 .

Since the moving part 340 moves the electrode assembly 10 as a whole with respect to the guide part 110 before welding by the welding part 120, it is similar to bending the electrode assembly 10 in the above-described embodiments. Specifically, the length of at least some of the electrode tabs 15 from the 'electrode assembly 10 to the assembly area (see G in FIG. 6B)' may be increased. In the embodiment of FIG. 8 , the lengths of all electrode tabs 15 may be increased.

The moving part 340 may include a seating part 340a provided to move along the stacking direction of the electrode assembly 10 in a state where the electrode assembly 10 is seated. The moving part 340 may include a support part 340b supporting the electrode assembly 10 in a direction opposite to the seating part 340a. The moving unit 340 may stably move the electrode assembly 10 through the support unit 340b. The support portion 340b may be provided to move in conjunction with the movement of the seating portion 340a in a state in which the electrode assembly 10 is pressed toward the seating portion 340a.

Example 4

Example 4 relates to a secondary battery, and may relate to a secondary battery manufactured by the above-described welding device/method. However, the device/method for manufacturing the secondary battery of Example 4 is not limited to the device/method described above.

As shown in FIG. 6C , the secondary battery of this embodiment may include an electrode assembly 10 and electrode tabs 15 protruding from the electrode assembly 10 . Further, the secondary battery of the present embodiment includes an exterior material 20 (see FIG. 1) accommodating the electrode assembly 10 and the electrode tabs 15, and an electrode lead 17 electrically connected to the electrode tabs 15 (see FIG. 1). reference) may be included. A part of the electrode lead 17 may be exposed to the outside of the exterior material 20 .

The electrode tabs 15 may be coupled to each other in a predetermined bonding area. The bonding area may be the aforementioned welding area (W).

A length of at least some of the electrode tabs 15 'from the electrode assembly 10 to the bonding area W' (see FIG. 6E ) may be longer than a predetermined reference length. Here, the length 'from the electrode assembly 10 to the bonding area W' is the length L from the electrode assembly 10 to the above-mentioned aggregation area G, and the aggregation area G to the bonding area W; welding area) may be the sum of the lengths. The reference length may be a minimum length from the electrode assembly 10 to the coupling region W (see FIG. 2d ). The reference length may be determined for each individual electrode tab. For example, the reference length may be calculated as a straight line length from a point where the corresponding electrode tab protrudes from the electrode assembly 10 to a point where the corresponding electrode tab is combined with another electrode tab. At this time, if necessary for calculating the exact straight line length, the reference length may be calculated in a state in which the electrode tab is pulled tight, for example, in a state in which the coupling point is pulled in a direction away from the electrode assembly.

For example, among the electrode tabs of FIG. 6C, the length L _T of the uppermost electrode tab from the electrode assembly 10 to the assembly region G, and the welding region W from the assembly region G ) 'is the length (L _T ' from the electrode assembly 10 to the assembly area) of the uppermost electrode tabs among the electrode tabs of FIG. 2B, and the welding area (Fig. 2d)) may be greater than the sum of the lengths. Similarly, the length L B of the lowermost electrode tab among the electrode tabs of FIG. 6C from the electrode assembly 10 to the assembly region _G , and the welding region W from the assembly region G The sum of the lengths from the electrode tabs in FIG. 2B is the 'length L _B' of the lowermost electrode tabs from the electrode assembly 10 to the assembly area and the length from the assembly area to the welding area. can be greater than the sum of For reference, in the above examples, 'lengths from the assembly area to the welding area' may be the same.

On the other hand, the increased length of at least some of the electrode tabs 15 'from the electrode assembly 10 to the bonding area W' increases along the stacking direction of the electrode and the separator (a vertical direction in FIG. It may increase as the electrode tab is located farther from . In FIG. 6C , since the bonding area W is located corresponding to the lowermost side of the electrode assembly 10 in the vertical direction, the increase length of the lowermost electrode tab is the shortest, and the increase length of the uppermost electrode tab is the longest. can be long

Here, the increased length may be a value obtained by subtracting the aforementioned reference length from the length from the electrode assembly 10 to the coupling region W. For example, in FIG. 6C, the increased length of the lowermost electrode tab is 'the length from the electrode assembly 10 to the assembly area G ( _LB ) + from the assembly area G to the coupling area W. It may be a value obtained by subtracting 'the length from the electrode assembly 10 to the assembly area ( _LB' ) + the length from the assembly area to the coupling area' of FIG. 2B from the 'length of'.

In the case of the embodiment of FIG. 6C , the bonding area W is located corresponding to the lowermost electrode tab of the electrode assembly 10 based on the vertical direction (the stacking direction of the electrode and the separator), and at this time, the number of electrode tabs increases. The length of the electrode tab located vertically upward may be longer. For example, the incremental length of the electrode tab located at the lowest side may be the shortest, and the incremental length of the electrode tab located at the uppermost side may be the longest. For reference, FIG. 6C may be applied to a type of pouch-type battery in which only one cup part for accommodating an electrode assembly is formed.

In FIG. 6C, the horizontal length of the support block 131 (the length of the surface horizontally disposed on the upper surface of the seating part) is X (unit: mm, hereinafter the same), and the vertical length of the support block 131 (the length of the surface of the seating part) When Y is the length of the surface disposed perpendicular to the upper surface of the portion), the length of the 'electrode assembly 10 to the bonding area W' of the electrode tabs located at the lowermost and uppermost sides, respectively ('total' in the table below) length') and increase length can be as shown in the table below. For reference, when Y is "0", since there is no bending by the support block 131, it can be a criterion for calculating the increased length as in the case of FIG. 2B or 2D. In addition, the table below relates to the positive electrode tab when the straight line distance in the horizontal direction from the electrode assembly to the assembly area (G; guide unit arrangement position) is 2.5 mm and the thickness of the electrode assembly is 10 mm.

the lowermost electrode tab				Uppermost electrode tab
X	Y	entire length	increase length	X	Y	entire length	increase length
3	0	5.50	-	3	0	8.59	-
3	3	8.15	2.65	3	3	12.62	4.03
3	4	9.72	4.22	3	4	14.34	5.75
3	5	11.42	5.92	3	5	16.14	7.55
3	6	13.21	7.71	3	6	17.99	9.40
3	7	15.05	9.55	3	7	19.87	11.28
4	0	6.50	-	4	0	9.59	-
4	3	8.91	2.41	4	3	13.38	3.79
4	4	10.37	3.87	4	4	15.00	5.41
4	5	11.99	5.49	4	5	16.71	7.12
4	6	13.71	7.21	4	6	18.49	8.90
4	7	15.50	9.00	4	7	20.32	10.73

As summarized in the table above, when X and Y are the same condition, the increase length of the upper electrode tab is greater than the increase length of the lower electrode tab. In addition, in the case of electrode tabs at the same position, if X is the same, the increase length of the electrode tab increases as Y increases, and this is the same for the lower electrode tab and the upper electrode tab. It can be seen that the increased length increases as the edge of the electrode assembly is bent higher. In addition, for the electrode tabs at the same position, if Y is the same, the increase length increases as the angle between the inclined surface 131a of the support block 131 and the lower surface of the support block 131 increases (for example, X is 3, Y is 4, and X is 4 and Y is 4), this is the same for the lower electrode tab and the upper electrode tab. It can be seen that the increase length increases as the edge of the electrode assembly is bent obliquely.

Meanwhile, the secondary battery of Example 4 may be modified as shown in FIG. 9 . 9 is a view for explaining a modified example of a secondary battery according to a fourth embodiment of the present invention.

In the case of the secondary battery described in FIG. 9, when the electrodes of the electrode assembly and the separator are stacked in a vertical direction (up and down directions in FIG. The electrode tabs located on the upper side and the electrode tabs located on the lower side of the reference plane P' may have asymmetrical lengths with respect to the reference plane. For example, in the case of the secondary battery manufactured as shown in FIG. 9 , when the support block 131 is removed and the electrode assembly is restored to its original shape, the uppermost point with respect to the reference plane P′ located at the middle height of the electrode assembly is restored. The electrode tab and the lowermost electrode tab may be symmetrically positioned, but the length L _T″ of the uppermost electrode tab may be longer than the length L _B″ of the lowermost electrode tab.

The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments.

The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

Claims (19)

1. In the electrode tab welding device for welding the electrode tabs protruding from the electrode assembly to each other,

   a guide unit provided to gather the electrode tabs in a predetermined gathering area;

   a welding portion provided to weld the electrode tabs collected by the guide portion; and

   And a bending portion provided to bend the electrode assembly so that a length from the electrode assembly to the assembly region is increased in at least some of the electrode tabs before welding by the welding portion.
2. The method of claim 1,

   The guide part,

   When the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, a plane parallel to the ground is lower than the reference plane passing through the center of the electrode assembly in the vertical direction. It is provided to gather the electrode tabs in an area,

   the bending part,

   An electrode tab welding apparatus provided to bend an edge of the electrode assembly to which the electrode tabs are connected upward.
3. The method of claim 1,

   the bending part,

   Considering that the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, a support block supporting one of the lower and upper surfaces of the electrode assembly, and the other one of the lower and upper surfaces of the electrode assembly An electrode tab welding device comprising a pressing block for pressing toward either side.
4. The method of claim 3,

   The point at which the support block supports any one of the lower and upper surfaces of the electrode assembly is located closer to the outer side of the electrode assembly than the point at which the pressing block presses the other one of the lower and upper surfaces of the electrode assembly , electrode tab welding device.
5. The method of claim 3,

   The support block is provided to support an edge of the electrode assembly to which the electrode tabs are connected from a lower side,

   The pressure block is provided to press the edge supported by the support block from the upper side to the lower side for the bending.
6. The method of claim 5,

   The support block is

   An electrode tab welding apparatus comprising an inclined surface that gradually increases in height toward the outer side of the electrode assembly as a surface located below the edge.
7. The method of claim 1,

   Further comprising a seating portion on which the electrode assembly is seated,

   the bending part,

   Considering that the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, they are disposed inside the seating part, and the lower surface of the electrode assembly protrudes to the upper surface of the seating part on which the electrode tabs are connected An electrode tab welding apparatus comprising a pressing block provided to press the edge of the electrode assembly from the lower side.
8. The method of claim 7,

   the bending part,

   The electrode tab welding apparatus further comprises a support block partially supporting an upper surface of the electrode assembly during pressing by the pressing block.
9. The method of claim 1,

   the bending part,

   When the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, including a support block provided to support the edge of the electrode assembly to which the electrode tabs are connected from the lower side, electrode tab welding device.
10. In the electrode tab welding device for welding the electrode tabs protruding from the electrode assembly to each other,

    a guide unit provided to gather the electrode tabs in a predetermined gathering area;

    a welding portion provided to weld the electrode tabs collected by the guide portion; and

    Before welding by the welding part, the electrode assembly is moved in a direction corresponding to the stacking direction of the electrode and the separator of the electrode assembly so that the length from the electrode assembly to the assembly area is increased in at least some of the electrode tabs. Electrode tab welding apparatus including a moving part for relative movement with respect to the guide part.
11. In the electrode tab welding method of welding the electrode tabs protruding from the electrode assembly to each other,

    (a) bending an edge of the electrode assembly to which the electrode tabs are connected; and

    (b) welding the electrode tabs in a bent state of the electrode assembly, the electrode tab welding method.
12. The method of claim 11,

    The electrode tab welding method further comprising a step of gathering the electrode tabs before the step (a) or between the steps (a) and the step (b).
13. The method of claim 11,

    After the step (b), further comprising the step of restoring the electrode assembly by removing the force applied to the electrode assembly for bending the electrode assembly in the step (a).
14. The method of claim 11,

    In the step (a),

    Considering that the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, in a state in which one of the lower and upper surfaces of the edge is supported, the other of the lower and upper surfaces of the edge toward the one A step of pressurizing, an electrode tab welding method.
15. The method of claim 14,

    The electrode tab welding method, wherein a point supporting one of the lower and upper surfaces of the edge is located closer to the outer side of the electrode assembly than a point for pressing the other of the lower and upper surfaces of the edge.
16. electrode assembly;

    electrode tabs protruding from the electrode assembly;

    an exterior material accommodating the electrode assembly and the electrode tabs; and

    An electrode lead electrically connected to the electrode tabs and partially exposed to the outside of the exterior material;

    The electrode tabs are coupled to each other in a predetermined bonding area,

    A length of at least some of the electrode tabs from the electrode assembly to the coupling region is longer than a predetermined reference length;

    The reference length is a minimum length from the electrode assembly to the coupling region in an individual electrode tab.
17. The method of claim 16

    The increased length of at least some of the electrode tabs from the electrode assembly to the bonding area increases as the electrode tab is located farther from the bonding area along the stacking direction of the electrode and the separator of the electrode assembly,

    The increased length is a value obtained by subtracting the reference length from a length from the electrode assembly to the coupling region.
18. The method of claim 17

    The bonding area is positioned to correspond to the lowermost electrode tab among the electrode tabs of the electrode assembly when the stacking direction is regarded as corresponding to the vertical direction,

    The increased length of the electrode tabs is longer as the electrode tabs located vertically upward.
19. The method of claim 16

    Considering that the electrodes and separators of the electrode assembly are stacked in a vertical direction, the electrode tabs located above the reference plane passing through the bonding area and orthogonal to the vertical direction and the electrode tabs located below the reference plane are A secondary battery having an asymmetrical length with respect to the reference plane.

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